Described herein is a process for improving the color of thermoplastic polymers by contacting the polymer with a peracid, hydrogen peroxide or other peroxygen compounds.
Thermoplastic polymers such as a polyarylate, poly(etherimide), polyester, aromatic polycarbonate, poly(aryl ether), etc., are high temperature, high performance thermoplastic polymers with a good combination of thermal and mechanical properties. However, many of the processes and/or raw materials used to produce these polymers can result in the production of a highly colored polymer. For example, polyarylates produced by the diacetate process have a tendency to be colored. Such colored polymers could be unsuitable for use in some end use applications.
The bleaching of synthetic polymers with hydrogen peroxide is usually limited to cotton-polyester blends because 100% synthetic fibers have a sufficient degree of whiteness and do not require bleaching. Only the cotton portion is bleached via this process. Only a relatively few attempts have been made to bleach synthetic fibers such as nylon and acrylic fibers with peracetic acid. No known attempts have been made to bleach aromatic polymers such as polyarylates, poly(aryl ethers), aromatic polycarbonates, etc. with the compounds of this invention.